So the text is probably 0,0,0 then?
You could try making it something like 20,20,20. That might already make some noticeable difference with the darkness of the stars.
But I now understand you predominantly mean the shape of the stars, and that you find them too 'fat'.
They are images, not glyphs of a font. So font settings will not make any difference to the size or shape of the stars.
The only option for this would be to request a skinning feature for skin designers to make it possible for them to design their own stars.
But I am guessing that is not very straightforward to implement, and if it would become a skinning option, my guess is that probably not many skinners will attempt to design their own stars. (I probably wouldn't)